1. Field of the Invention
The present invention relates to the BaTiO3xe2x80x94PbTiO3 series single crystal that can be utilized as a piezoelectric element, for example, and also, relates to the method of manufacturing the same. Further, the invention relates to a piezoelectric type actuator formed by the BaTiO3xe2x80x94PbTiO3 series single crystal, and the liquid discharge head that uses such piezoelectric type actuator as well.
2. Related Background Art
The BaTiO3 series single crystal is a nonlinear optical crystal utilized for optical communications, information processing, or the like, and having a great marketability, which is not only used as a phase conjugate wave generating medium for a high resolution image processing, a real-time hologram, or a laser resonator, but also, used as a highly capable piezoelectric material if the crystallization thereof can be implemented at lower costs.
Now, obviously, the composition of the BaTiO3 makes it difficult to obtain single crystal directly from the BaTiO3 solution when BaTiO3 series single crystal is manufactured. Therefore, only the flux growth that uses solution (flux) having fluoride and chloride as main component or the method, in which the BaTiO3 series single crystal of low-temperature component is picked up directly by making the composition of the solution TiO2 rich (the so-called top seeded solution growth (TSSG method)), is applicable to the growth thereof. With the flux growth, the obtainable size is only 1 mm3 or less approximately. Also, for the TSSG method, not only an expensive noble metal crucible, such as a platinum crucible, is needed, but the growing speed is slow to make the manufacturing costs extremely high.
Conventionally, it has been attempted to provide a method for manufacturing larger BaTiO3 series single crystal more effectively and easily with the improvement of the aspects that present the problems as described above.
For example, there are experiments carried out in manufacturing BaTiO3 series single crystal efficiently by sintering method. In the specifications of Japanese Patent Application Laid-Open Nos. 4-300296, 5-155696 and 5-155697, a method for manufacturing BaTiO3 series single crystal is disclosed, in which the BaTiO3 series single crystal serving as the seed crystal is coupled with the BaTiO3 polycrystal, and heated to mono-crystalize such polycrystal by means of solid-phase reaction. In the specification of Japanese Patent Application Laid-Open No. 9-263496, a method for manufacturing BaTiO3 series single crystal is disclosed, in which a temperature gradient is given to the BaTiO3 micro-crystal granular aggregate, the mol ratio of Ti/Ba of which is 1.0 or more and 1.1 or less, for the execution of single crystallization thereof. With these methods, however, the mono-crystalline growth rate greatly varies to make it impossible to grow any bulky single crystal with good reproducibility. Also, the rearrangement density is high, and the crystallinity of the BaTiO3 series single crystal thus obtained is inferior to the one obtained by the conventional TSSG method and the flux method. There are also the examples of solid-phase methods other than the sintering method. In the specification of Japanese Patent Application Laid-Open No. 59-3091, there is the disclosure of a method for manufacturing the oxide single crystal, in which a crystal oxide, such as PbTiO3, BaTiO3, SrTiO3, CaTiO3, is quenched and solidified after molten to make it amorphous, and then, re-crystallized under a temperature gradient. This method makes the manufacturing apparatus and process complicated, because there is a need for a process to melt the crystal oxide. Also, the single crystal thus obtained has inferior crystallization properties, and only the crystal that has a high ratio of pore content is obtainable eventually.
Also, improvement studies have been made on the TSSG method and the flux method. In the specification of Japanese Patent Application Laid-Open No. 6-321698, there is disclosed, as the flux method, a method for manufacturing BaTiO3 using a mixed substance of BaF2, NaF, Li2MoO4, or the like as flux. In this method, the solubility of BaTiO3 is enhanced for the purpose of obtaining bulky BaTiO3 series single crystal with a long-time crystal growth. However, this method is not fully satisfactory in terms of the time required for manufacturing and costs. In the specification of Japanese Patent Application Laid-Open No. 9-59096, there is disclosed BaTiO3 series single crystal having the doping of fine quantities of Mg and Fe. This material aims at obtaining a high photo-refractivity in the near infrared range, but Mg, Fe, or some other element, which may exert unfavorable influence on the piezoelectric property, is contained in that material. As a result, it is not preferable to use this as a piezoelectric material. Also, for the utilization at the industrial level, it is not satisfactory in terms of the time required for manufacture and costs.
As described above, the TSSG or flux method for manufacturing BaTiO3 series single crystal makes it extremely difficult to improve problems related to manufacturing efficiency, such as the time required for manufacturing and costs, among some others. Here, although the sintering method is anticipated to enhance the manufacturing efficiency, the variation of growing speed of BaTiO3 series single crystal makes it impossible to obtain any satisfactory result, and also, the crystallinity of the BaTiO3 series single crystal thus obtained is inferior to the one obtainable by means of TSSG or flux method. In other words, it has been difficult to implement the manufacture of BaTiO3 series single crystal having excellent crystallinity and property in a shorter period of time at lower costs.
For the formation of BaTiO3 series single crystal by sintering method, the inventors hereof have attempted to make the enhancement of the reproducibility of single crystal growth compatible with the enhancement of crystallinity and other substances by adding other component to BaTiO3 itself. With this in view, the inventors hereof have studied assiduously, with the result that a system, in which PbTiO3 is added to BaTiO3, is found to enable a crystallization growth to occur with an extremely fine reproducibility, satisfied only with a predetermined condition Therefore, the studies have been made further in detail on the BaTiO3xe2x80x94PbTiO3 system to design the present invention completely.
The inventors hereof have measured the crystallinity of the BaTiO3xe2x80x94PbTiO3 series single crystal obtained in accordance with the present invention. As a result, it is found that the BaTiO3xe2x80x94PbTiO3 of the present invention is extremely fine in the crystallinity thereof. It is also confirmed by the X-ray diffraction and electron beam diffraction that the crystal orientation of the single crystal is completely coincident. Also, by the observation of etch pit, which will be described later, it is confirmed that the rearrangement density of the crystal is low, and that from this observation, the excellent crystal has a small amount of lattice defect. The ratio of pore content is also extremely small.
Following this, the other properties of the BaTiO3xe2x80x94PbTiO3 series single crystal, such as permittivity, piezoelectric property, and pyroelectric property, among some others, are examined. As a result, it is found that the piezoelectric property is excellent in particular, which is far superior to the property of PZT (Pb (Ti, Zr) O3) polycrystal currently used as standards, or that of BaTiO3 series single crystal manufactured by means of the TSSG method, not to mention that of BaTiO3 polycrystal.
From the viewpoint of the BaTiO3xe2x80x94PbTiO3 series single crystal as a piezoelectric material, it has such advantages as the wide range of temperatures at which it can be used, and the lower amount of lead content that it has attained, as well as the excellent piezoelectric property that it can provide. The curie temperature of BaTiO3 series single crystal is approximately 120xc2x0 C. (Tc). Any element that uses the BaTiO3 series single crystal has a narrow usable temperature range due to low Tc as practical drawbacks. The BaTiO3xe2x80x94PbTiO3 series single crystal of the present invention has a higher curie temperature (Tc) than the aforesaid BaTiO3 polycrystal to make it possible to make the range of usable temperature larger.
Also, in order to reduce the load to the environment on earth, it is required to reduce the amount of lead to be used for any industrial product in recent years. As compared with the PZT polycrystal, which presents the main current of piezoelectric material at present, the BaTiO3xe2x80x94PbTiO3 series single crystal of the present invention is found to be able to reduce the use amount of lead significantly owing to the composition that is different therefrom, and further, to enhance the piezoelectric property conspicuously. Also, it has been found that the use amount of piezoelectric material itself, which is needed for producing the same effect, is reduced significantly. At present, it is considered to use BaTiO3 polycrystal, Bi0.5Na0.5TiO3 series single crystal (Na0.5K0.5) NbO3 polycrystal as a promising material for substitution of PZT for the purpose of reducing the lead use amount. However, against the PZT piezoelectric constant d33=300 to 400 (xc3x9710xe2x88x9212 C/N) and electromechanical coupling coefficient k33=0.6 to 0.7, the BaTiO3 polycrystal has the piezoelectric constant d33=120 (xc3x9710xe2x88x9212 C/N) and electromechanical coupling coefficient k33=0.4 to 0.5, and the BiO5Na05TiO3 has the piezoelectric constant d33=110 (xc3x9710xe2x88x9212 C/N) and electromechanical coupling coefficient k33=0.4 to 0.6. Therefore, the piezoelectric property is not satisfactory.
Also, the piezoelectric property of the BaTiO3xe2x80x94PbTiO3 polycrystal is far inferior in terms of a piezoelectric material to that of the PZT polycrystal or the BaTiO3xe2x80x94PbTiO3 series single crystal, and there is no way fundamentally to enhance the piezoelectric property as single crystal. It is also considered more difficult to manufacture BaTiO3xe2x80x94PbTiO3 series single crystal by the method other than the one designed by the present invention, such as the flux method, the TSSG method, or any other melt-solidification method than to manufacture BaTiO3 series single crystal. There is no value that can be found in these methods. As described earlier, regarding the BaTiO3 series single crystal, only the small one, the size of which is approximately 1 mm3 or less, is obtainable by means of the flux method. Also, for the TSSG method, an expensive noble crucible, such a platinum crucible, is needed. In addition, the growing speed is only 0.1 to 0.2 mm/h approximately, leading to an extremely high cost of manufacture. Further, the material loss is great, and there is a drawback that it is difficult to obtain bulky crystal. Such an extremely high cost of manufacture is inevitable to make the field of utilization thereof extremely limited. It has been pointed out that this is valueless as a material of industrial use. On the functional aspect, too, impurities tend to be mixed during the single crystal growing process. There are often the cases where the anticipated performance cannot be demonstrated after all. It is also anticipated that there is the same problem regarding the BaTiO3xe2x80x94PbTiO3 series single crystal if it should be manufactured using the melt-solidification method.
As the example of a method for manufacturing perovskite oxide single crystal, there is the disclosure in the specification of Japanese Patent Application Laid-Open No. 9-188597, in which a process is provided for enabling the perovskite sintered member of Pb {(Mg1/3Nb2/3)1-xTix}O3 (in the aforesaid composition formula, 0xe2x89xa6xxe2x89xa60.55. Pb of 10 mol % or less may be replaced with Ba, Sr, Ca, or the like) to be in contact with seed crystal, and heated at a temperature of 1,000 to 1,450xc2x0 C. in the closed container in the lead atmosphere. However, there is no disclosure of the BaTiO3xe2x80x94PbTiO3 series single crystal having a smaller mol number of Pb than that of Ba. There is also no disclosure as to the effect thereof as a matter of course. Also, when the ratio between the A site and B site of the aforesaid perovskite sintered member is 1.00 greater than A/B, the crystallization speed is remarkably slow. This is the tendency that differs from the present invention as described later.
It is an object of the present invention to improve the dielectric loss and electromechanical coupling coefficient, and provide excellent BaTiO3xe2x80x94PbTiO3 series single crystal in various properties, such as permittivity, piezoelectric property, pyroelectric property, and also, to provide BaTiO3xe2x80x94PbTiO3 series single crystal as the piezoelectric material having a small ratio of lead content, which is particularly excellent in piezoelectric property and productivity. It is another object of the invention to provide a method for manufacturing BaTiO3xe2x80x94PbTiO3 series single crystal capable of manufacturing BaTiO3xe2x80x94PbTiO3 series single crystal efficiently, not by means of the single crystal growth using the melt-solidification method. It is still another object of the invention to provide a piezoelectric type actuator using the BaTiO3xe2x80x94PbTiO3 series single crystal, and a liquid discharge head as well.
The BaTiO3xe2x80x94PbTiO3 series single crystal of the present invention is single-crystallized by heating BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member having a smaller Pb-containing mol number than Ba-containing mol number, while keeping the powder or member in non-molten condition. The inventors hereof have found that it becomes possible for the conventional manufacture of BaTiO3 series single crystal by means of the sintering method, which is unable to grow single crystal with good reproducibility, to perform a stable single crystal growth by adding PbTiO3 to BaTiO3 so that the Pb-containing mol number is made smaller than the Ba-containing mol number, hence designing the present invention completely.
It is preferable for the BaTiO3xe2x80x94PbTiO3 series single crystal of the invention that the rearrangement density is 102 pieces/cm2 or more and 106 pieces/cm2 or less, and the ratio of pore content is within a range of 1 volume ppm or more and 5 volume % or less. In this way, the BaTiO3xe2x80x94PbTiO3 series single crystal of the invention makes the dielectric loss smaller, and the electromechanical coupling coefficient larger. For example, the dielectric loss is 1% or less, and the electromechanical coupling coefficient exceeds 85%.
It is preferable for the BaTiO3xe2x80x94PbTiO3 series single crystal of the invention that the ratio of PbTiO3 content is 45 mol % or less in the BaTiO3xe2x80x94PbTiO3 series single crystal. When the ratio of PbTiO3 content in the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member, which serves as the starting substance, is arranged to be 45 mol % or less, the single crystal growing speed is promoted more to make it possible to manufacture the single crystal substance more stably. Then, the resultant ratio of PbTi3 content in the BaTiO3xe2x80x94PbTiO3 series single crystal is the same as the ratio of PbTiO3 content in the starting substance. It is preferable for the BaTiO3xe2x80x94PbTiO3 series single crystal of the invention that the ratio of PbTiO3 content is 30 mol % or less, and more preferably, it is 25 mol % or less. If the ratio of PbTiO3 content is too much, the evaporation of Pb becomes conspicuous, and composition changes from the target one, while the single crystal thus obtained tends to become porous. In order to suppress the Pb evaporation, it is imperative that a pressurized container be utilized, presenting a disadvantage that the manufacturing costs become higher. Also, the minimum amount of PbTiO3 content in the BaTiO3xe2x80x94PbTiO3 series single crystal of the invention should preferably be 0.01 mol % or more, and more preferably, it is 0.02 mol % or more.
It is preferable for the BaTiO3xe2x80x94PbTiO3 series single crystal of the invention that the volume of the single crystal is 1 mm3 or more. The volume of the BaTiO3xe2x80x94PbTiO3 series single crystal of the invention can easily be made 1 mm3 or more with the stable crystal growth. With the volume of 1 mm3 or more, the single crystal makes it possible to favorably deal with many devices in various sizes due to the area that can be made larger. Also, according to another mode of the present invention, the BaTiO3xe2x80x94PbTiO3 series single crystal is characterized in that the rearrangement density of 102 pieces/cm2 or more and 106 pieces/cm2 or less, and the ratio of pore content being within in a range of 1 volume ppm or more and 5 volume % or less. More preferably, the ratio of PbTiO3 content is 45 mol % or less for the BaTiO3xe2x80x94PbTiO3 series single crystal of the invention. In this way, the BaTiO3xe2x80x94PbTiO3 series single crystal of the invention makes the dielectric loss smaller, and the electromechanical coupling coefficient larger.
Also, the method of the present invention for manufacturing BaTiO3xe2x80x94PbTiO3 series single crystal comprises the step of single-crystallizing BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member having a smaller Pb-containing mol number than Ba-containing mol number by defining the range of the mol ratio of elements contained therein to be 0.9800 less than (Ba+Pb)/Ti less than 1.0000, and by heating, while keeping the powder or substance in non-molten condition. More preferably, the range of the mol ratio of elements contained in the compact powder member or sintered member is defined to be 0.9900 less than (Ba+Pb)/Ti less than 1.0000. Still more preferably, the range of the mol ratio of elements contained in the compact powder member or sintered member is defined to be 0.9950xe2x89xa6(Ba+Pb)/Tixe2x89xa60.9999. By heating the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member having a smaller Pb-containing mol number than Ba-containing mol number, while keeping it in non-molten condition, the reproducibility of single crystal growth is enhanced as compared with the same process of only the BaTiO3 compact powder member or sintered member that does not contain PbTiO3, thus making it possible to manufacture the stable BaTiO3xe2x80x94PbTiO3 series single crystal. Further, by defining the mol ratio of elements contained in the BaTiO3xe2x80x94PbTiO3 series single crystal within a specific range, the crystal growing speed of BaTiO3xe2x80x94PbTiO3 series single crystal becomes faster.
It is preferable for the method of the present invention for manufacturing BaTiO3xe2x80x94PbTiO3 series single crystal that the ratio of PbTiO3 content is 45 mol % or less in the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member. When the ratio of PbTiO3 content in the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member, which serves as the starting substance, is arranged to be 45 mol % or less, the single crystal growing speed is promoted more to make it possible to manufacture the single crystal substance more stably. It is preferable for the method of the invention for manufacturing BaTiO3xe2x80x94PbTiO3 series single crystal that the ratio of PbTiO3 content in the BaTiO3xe2x80x94PbTiO3 series single crystal compact powder or sintered member is 30 mol % or less, and more preferably, it is 25 mol % or less. If the ratio of PbTiO3 content is too much, the evaporation of Pb becomes conspicuous, and composition changes from the target one, while the single crystal thus obtained tends to become porous. In order to suppress the Pb evaporation, it is imperative that a pressurized container be utilized, presenting a disadvantage that the manufacturing costs become higher. Also, in the method for manufacturing BaTiO3xe2x80x94PbTiO3 series single crystal, the minimum amount of PbTiO3 content in the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member should preferably be 0.01 mol % or more, and more preferably, it is 0.02 mol % or more.
It is preferable for the method of the present invention for manufacturing BaTiO3xe2x80x94PbTiO3 series single crystal to comprise the step of single-crystallizing by heating the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member within a temperature range of 1,200xc2x0 C. or more and 1,400xc2x0 C. or less. By heating the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member within a range of designated temperatures, the crystal growing speed of BaTiO3xe2x80x94PbTiO3 series single crystal becomes faster.
Further, the method of the present invention for manufacturing BaTiO3xe2x80x94PbTiO3 series single crystal comprises the steps of preparing BaTiO3 series single crystal or BaTiO3xe2x80x94PbTiO3 series single crystal as seed crystal; coupling BaTiO3xe2x80x94PbTiO3 series sintered member composed of crystal grain of average granular diameter of 20 xcexcm or less, having the relative density of 95% or more, with the {100} plane, {110} plane, or {111} plane of the seed crystal; and single-crystallizing by heating, while keeping the coupled substance in non-molten condition. More preferably, the mol ratio of elements contained in the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member is within a range of 0.9950xe2x89xa6(Ba+Pb)/Tixe2x89xa60.9999. In the method of the invention for manufacturing BaTiO3xe2x80x94PbTiO3 series single crystal, the single crystallization takes place stably from the coupling portion between the compact powder member or sintered member and the seed crystal by use of the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member coupled with the seed crystal in the aforesaid condition, and the reproducibility of single crystal growth is enhanced. Also, if the mol ratio of elements contained in the aforesaid compact powder or sintered member is within the designated range, the crystal growing speed of BaTiO3xe2x80x94PbTiO3 series single crystal becomes faster still.
It is preferable for the method of the present invention for manufacturing BaTiO3xe2x80x94PbTiO3 series single crystal to comprise the step of single-crystallizing by heating, while keeping the compact powder member or sintered member in the lead atmosphere and in non-molten condition. As one of the methods for forming the lead atmosphere, it is possible to evaporate lead or lead oxide form the lead-contained compound by enabling the lead-contained compound to coexist in the environment in which the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member is heated, while being kept in non-molten condition. By heating the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member in the lead atmosphere, it becomes possible to prevent lead, lead oxide, or the like from being evaporated from the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member or the BaTiO3xe2x80x94PbTiO3 series single crystal. In this way, the increase of rearrangement density and the ratio of pore content in the BaTiO3xe2x80x94PbTiO3 series single crystal can be suppressed, thus making it possible to manufacture high quality BaTiO3xe2x80x94PbTiO3 series single crystal.
Further, the piezoelectric type actuator of the present invention comprises a layer formed by BaTiO3xe2x80x94PbTiO3 series single crystal described earlier. Also, the liquid discharge head of the present invention comprises the aforesaid piezoelectric type actuator. Here, the piezoelectric type actuator and liquid discharge head of the present invention use the BaTiO3xe2x80x94PbTiO3 series single crystal that has high electromechanical coupling coefficient, high piezoelectric constant, and high curie temperature altogether as the piezoelectric material. Thus, the piezoelectric actuator and liquid discharge head can be materialized to provide high output with a wide range of usable temperatures. Also, from the viewpoint of the environmental improvement on earth, it is preferable to use the aforesaid actuator and head, because the amount of lead contented in them is small.
The BaTiO3xe2x80x94PbTiO3 series single crystal of the present invention is single-crystallized by heating BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member having a smaller Pb-containing mol number than Ba-containing mol number, while keeping the powder or substance in non-molten condition. The effect of the reproducibility of the crystal growth of the present invention cannot be demonstrated even if the method of manufacture thereof is applied to the compact powder member or sintered member composed of only BaTiO3. Although the mechanism thereof has not been confirmed as yet, it is inferred as given below. When the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member is heated, while kept in non-molten condition, lead or lead compound is evaporated from the surface of the powder or signatured substance, and externally dispersed, and the deficiency of lead ensues on the surface of the compact powder member or sintered member. Thus, lead shifts from the inside of the compact powder member or sintered member to the surface to compensate for the deficiency thereof. At this juncture, the granular interface in the inside of the compact powder member or sintered member tends to move easily, hence enabling the crystal growth to occur stably.
The BaTiO3xe2x80x94PbTiO3 series single crystal of the present invention can be manufactured at a crystal growing speed faster still by preparing the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member, which serves as starting substance, with a designated composition as described earlier or by heating it within a designated range of temperatures. The BaTiO3xe2x80x94PbTiO3 series single crystal of the present invention can be manufactured with a crystal growing speed stabilized more by coupling a designated single crystal as a seed crystal with the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member, which serves as starting substance. FIGS. 2A to 2D are views that illustrate the state of the crystal growth when the BaTiO3xe2x80x94PbTiO3 series single crystal of the present invention is manufactured, in which the designated single crystal 22 is coupled with the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member 24, and heated in non-molten condition. As shown in FIG. 2B, it is understandable that on the coupling portion of the BaTiO3xe2x80x94PbTiO3 compact powder member or sintered member with the seed crystal, particularly on the circumferential area thereof, the crystal growth occurs conspicuously. Conceivably, this is because the shift of lead occurs intensively particularly on the aforesaid circumferential area, and also, conceivably, this is the phenomenon that supports the aforesaid mechanism of crystal growth. Typically, in FIG. 2C, a reference numeral 26 designates the single-crystallized portion, and 28, the polycrystal portion.
In accordance with the present invention, it is possible to provide the BaTiO3xe2x80x94PbTiO3 series single crystal having the property comparable to the PZT material already made available as a Pb-less piezoelectric material that serves the purpose of reducing the harmful substance, such as Pb in PZT, among some others. Also, along with the increased amount of Pb-containing, the curie temperature becomes higher, but it is possible to select the curie temperature up to approximately 300xc2x0 C. appropriately, thus presenting no problem as to the curie temperature. Also, the BaTiO3xe2x80x94PbTiO3 series single crystal manufactured by the sintering method has a smaller dielectric loss, and the amount of inductive distortion increases at the time of electric field application due to significant rising of electro-mechanical coupling coefficient along with the extinction of granular boundaries of the largely oblique-angled ones, hence presenting extremely favorable piezoelectric property.
Further, in accordance with the method of manufacture of the present invention, it is possible to obtain high quality BaTiO3xe2x80x94PbTiO3 series single crystal by preparing the seed crystal having bulky grain formed by sintering compact powder member, the specific composition range of which is (Ba+Pb)/Ti ratio, or by preparing the seed crystal by means of the conventional melt-solidification method, and also, producing the BaTiO3xe2x80x94PbTiO3 series sintered member, which is given the same composition adjustment, and then, by giving heat treatment subsequent to the coupling of the seed crystal and the sintered member. The growing speed of single crystal by means of this sintering method is comparable to that of the Melt-Growth method or superior thereto, and the property of this single crystal is far superior to that of the PZT sintered member currently available.
Also, it is possible to process many numbers of samples by sintering method at a time, thus not only contributing to reducing the production cost significantly, but also, making the productivity and the maintenance of property compatible so as to keep the rearrangement density in crystal in an extremely small amount, and attain the high quality thereof.